Electrical connectors are commonly used in the electronics industry in order to facilitate the interconnection of various components, usually by a plurality of conductive wires. Such connectors are typically formed as a row of a specified number of positions, with each position containing one or more connection sites. For example, a twelve position dual in-line connector will have twelve positions of two pins or connection sites each, for a total of 24 pins or connection sites. Similarly, a twelve position single in-line connector will have twelve positions for a single pin or connection site, for a total of 12 pins or connection sites.
Electrical connectors may generally be divided into two classes: through-hole connectors and surface mounted connectors. Surface mount connectors include a conductive lead for each position protruding from the bottom surface of the connector. Each lead is formed in a curved configuration such that the lead rests on a conductive pad on the surface of the printed circuit board. The surface mount leads are soldered to these conductive pads.
Through-hole connectors, on the other hand, include a row of conductive pins which protrude from their bottom surfaces and extend through holes formed in the printed circuit board to which the through-hole connector is mounted. Each of these pins is soldered to a conductive trace on the opposite side of the printed circuit board from this connector body. For example, if a through-hole connector has 24 pins, twenty-four through-holes will be formed in the printed circuit board with the same dimensional spacing between the through-holes as between the connector pins. In addition, a through-hole connector may have a pin protruding from the top of the connector body to allow a second printed circuit board to be mounted as described above and therefore electrically connected to the first board. Finally, a through-hole connector may include two or more rows of positions adjacent to and aligned with the original row.
When a through-hole connector is mounted onto a printed circuit board, each of the connector pins extend through a respective through-hole in the printed circuit board. There can therefore be no misalignment between the mounted connector and the printed circuit board, because the through-holes positively locate the connector mounting position. This feature makes through-hole connectors particularly advantageous over surface mount conductors to some manufacturers.
One disadvantage with the electrical connectors described above is that the end user may have a need for a number of connectors with a different number of positions. This requires either the connector manufacturer or purchaser, or both, to maintain a substantial inventory of electrical connectors with various lengths and numbers of positions.
Another disadvantage to electrical connectors having varying length requirements is that the manufacture of these connectors often results in wasted scrap material. For example, if the standard connector body includes 50 positions, and the end-user requires a 20 position connector, then two connectors may be formed therefrom, with twenty percent (20%) of the original connector having to be scrapped.
One attempt to address the foregoing shortcoming is disclosed in U.S. Pat. No. 4,832,622 to Zann. This patent discusses a continuous connector header via an extrusion or injection molding process. After the continuous body is formed, it is then drilled (if necessary) for the insertion of pins, or otherwise modified for insertion of other devices. The end user may then "cut to position" in order to form a connector with the desired number of positions.
While the foregoing prior art addresses some of the problems in manufacturing electrical connectors, it is not entirely satisfactory. First, continuous extrusion and injection molding techniques are very expensive, particularly when manufacturing a through-hole connector. It is much more cost effective to manufacture discrete, uniform header segments of a finite length (so long as potential scrap and inventory costs are not considered.) Second, the continuous manufacturing techniques involve a more difficult manufacturing process, which presents additional problems concerning quality control. For instance, if a defect is found in a continuous reel, then manufacturing must be stopped, or the entire reel may be unusable.
There is therefore a need in the prior art for a continuous electrical connector design that eliminates the scrap and inventory problems created by the varying position and length requirements of end-users, but is inexpensive and simple to manufacture. Such a design should also be readily integratable into existing manufacturing techniques. A need also exists for a continuous electrical connector design that allows continuation of the quality known by existing connector body designs and manufacturing techniques. The present invention is directed toward meeting that need.